This invention relates generally to the processing of municipal waste, to reduce the amount of material being placed into landfills and, more particularly, to a process by which the reclamation of materials of value from the municipal waste can be enhanced.
While re-cycling of materials of value, including glass, plastic, steel (such as cans) and aluminum, from municipal waste has been done in the past, the process has been generally labor intensive and marginally profitable. Some re-cycling efforts have been started at the home and office, by segregating materials of value to be collected independently of the remaining trash materials, yet participation is irregular and too much municipal waste is still placed into landfills that are overburdened and potential sources of water pollution.
Composting has been used for many years to reduce trash materials into an organic material that can be safely discharged to the ground. Composting has recently been on the increase at municipal sites where large composting vessels and/or static compost piles are being used to reduce the amount of material being deposited into the landfill and to increase the amount of materials being re-cycled. Substantially any organic material can be composted, provided an adequate quantity of carbon material is provided with access to air. Carbon sources include paper, cardboard, grass clippings, leaves, hay, straw, wood chips and sawdust, among many others. Many of these sources of carbon for effective composting is found in municipal waste, particularly paper and cardboard. Accordingly, composting presents an effective process for re-cycling materials and reducing the volume of material being placed into the landfills.
Many other materials of value are still available in municipal waste, despite the efforts to require segregation of such materials at the point of origin. Labor intensive practices will not be cost effective to reclaim these materials of value. Accordingly, an improved process through which a greater amount of materials of value can be reclaimed at a cost effective manner is highly desirable.
It is an object of this invention to provide a method for processing municipal waste to reduce the volume of materials being sent to a landfill for final disposition.
It is another object of this invention to provide a method of processing municipal waste that increases the extraction of materials of value to provide an income source for establishing the process.
It is a feature of this invention that mechanical devices can be utilized to extract materials of value from the waste material stream throughout the process.
It is an advantage of this invention that labor used for processing municipal waste is reduced.
It is still another object of this invention to compost the small and fine materials divided out of the stream of waste material.
It is another feature of this invention that composting vessels can be utilized to compost waste material on an on-going basis.
It is still another feature of this invention that the number of composting vessels can be matched in processing time to a shredding mechanism to form a cell.
It is another advantage of this invention that the compost developed from this process can be sold as a commercial grade compost.
It is a yet another object of this invention to provide a method of processing municipal waste that provides an initial disintegration and a destruction of pathogens within the waste material stream.
It is yet another feature of this invention to utilize a steam pressure vessel to disintegrate the waste materials and to destroy pathogens.
It is still another advantage of this invention that the composting step can be used early in the process before materials of value are extracted or late in the process after materials of value have been extracted.
It is a further object of this invention to provide apparatus for accomplishing this process of handling municipal waste to increase the volume of extracted materials of value and to reduce the volume of materials being disposed in a landfill which is durable in construction, inexpensive of manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use.
These and other objects, features and advantages are accomplished according to the instant invention by providing a method for processing municipal waste which substantially reduces the volume of material to be disposed into a landfill by increasing the volume of materials of value collected from the municipal waste and by composting the remaining materials to create a salable product. The process includes the removal of materials of value by magnetic devices to extract ferrous materials, by an air classifier to extract light plastic materials, by an eddy current mechanism to extract aluminum materials, and by a plastic sort mechanism to extract large plastic materials. Composting can be accomplished with a composting vessel that is located in the process either before the materials of value are removed or afterward. A grinding of the materials before a final screening allows the commercial grade compost to be separated from the materials that are to be sent to the landfill for final disposal. An alternative embodiment of the process heats the waste material before processing by utilizing a steam pressure vessel or an autoclave to disintegrate the waste material and to destroy any pathogens before materials of value are removed. Large materials can be gasified to create heat energy for use in the heating process. Static pile disintegration of the initially shredded waste material will alternatively reduce the volume of the material to be processed.